Method of preparing paper for photographic printing



s ren STATES PATENT OF ICE.

REDFIELD B. VEST, OF GUILFORD, CONNECTICUT.

METHOD OF PREPARING PAPER FOR PHOTOGRAPHIC PRINTlNG.

SIECEPICATION forming part of Letters Patent No. 341,083, dated May 4-,1836.

Application filed June 1, 1885. Serial No. 167,290. (No specimens.)

T aZZ 1071/0727, it may concern:

Be it known that I, Rennrnnn B. \Vnsr, of Guilford, in the county of NewHaven and State of Connecticut, have invented a new Iniprovement in thePreparation of Paper for Photographic Printing; and I do hereby declarethe following to be a full, clear, and exact description of the same.

This invention relates to an improvement in the preparation of paper forprinting photographs, the paper being specially adapted to photographicprinting under the process for which Letters Patent No. 273.206 weregranted to me February 27, 1883, parts of the invention, however, beingapplicable to other processes of printing; and the invention consists incoating both sides of the paper with a preparation of starch, ashereinafter more fully described.

The paper to which my preparation is best adapted is that known in themarket as B. F. K. lticves, No. 74-.

The bath in which the paperis to be coated is prepared after thefollowing formula: Potato starch, six ounces; glycerine, two ounces;sodium citrate,(nearlybut not quite neutrah) one-fourth ounce; purewater, two hundred and twenty ounces.

To prepare the bath, take, say.onc-tenth of the water, boil it to expelthe air, then cool. In this mix the starch, glycerine, and citrate. Heatthe remainderof the water until it boils. Then remove from the fire andimmediately add the ingredients so previously mixed with the firstportion of water. Care should be taken that there be no lumps in themixture with the first portion of water, but that it be perfectlysmooth. If the mixture is to bekept for a considerable length of timebefore use,it should be brought to a temperature a little abovebloodheat-say 105 Fahrenheit-and this is the best temperature at whichto dip the paper; but before the paper is dipped the bath should befiltered through fine muslin, and so as to avoid air-bubbles in thebath. The bath warmed to about blood heat should be arranged where thereis a good light in order to observe the operation.

The paper is best applied by holding the sheet perpendicularly over thebath, letting one edge fall upon the surface face downward.

Then carefully and by degrees bring the paper onto the surface; but thismust be done so slowly and evenly that no ai r can come between thesurface of the bath and the paper. This is best done by employing aglassbar or other suitable device which is straight upon its edge, to bedrawn over the back of the paper as the paper is permitted to fall uponthesurface of the bath, so that such movement of the bar -over the backof the paper will force the air forward and prevent bubbles formingbeneath the paper. This depression should be such as to surely take theentire su rfacc of the paper upon the batlnaud to insure this thepressure may be such as to carry the paper slightly be low the plane ofthe surface of the bath, but not so low as to permit the fluid to flowover the upper surface. After the onesurface has been thus presented tothe bath and completely coated, the sheet is at once removed and inverted, presenting the other side, which is allowed to float for a fewseconds on the surface, and then the paper, thus having both sidescoated with the composition of the bath, is suspended and dried, and forthe best results the drying should be rapid.

It is disadvantageous to permit the bath of starch composition to cooland be rewarmed, as this is liable to produce a rough or streaky paper.In some cases I have found that the starch shows a tendency to ru u downin streaks when applied to the paper. This is caused either by dryingtoo slowly or by impurities in the bath or paper, or possibly by thecomposition of the bath being too thin. This tendency is obviated orreduced by the addition of citric acid in solution and in smallquantities. The paper is thus coated with the starch composition uponboth surfaces.

The preparation for printing may be that in accordance with my previouspatent or otherwise; but after printing the prints are mounted bymoistening the starched surface of the back, and then applying itdirectly upon the board.

Under my process of printing the print is ready to mount as soon as itcomes from the bath, it not requiring to be dried, as in com- IOObelieve the proportions namel will produce 15 the best results.

I claim The herein-described improvement in the preparation of paper forphotographic printing, consisting in subjecting both surfaces of 20 thepaper to a bath composed of starch, glycerine, sodium citrate, andwater, in the proportions substantially as described.

REDFIELD B. VEST.

Vitnesses:

CHRISTOPHER SPENCER, FRED O. SPENCER,

